V. h. f. television antenna



Feb. 3, 1959 G. P. KEARSE 2,872,531

v. H. F. TELEVISION ANTENNA Filed Dec. 22, 1955 Fig. I

INVENTOR.

GEORGE I? KEARSE Fig 2 I ATTORNEY V. H. F. TELEVEEQN ANTENNA George P. Kearsc, Chicago, ilL, assignor, by mesne assignments, to Finney Manufacturing Qornpany, Jiereiand, @lrio, a corporation of Ohio Application December 22, 1955, Serial No. 554,388

Thev terminal portion of the term of the patent subsequent to September 12, 1972, has been disclaimed 11 Claims. ('(ll. 343-833) several factors. For one thing, the range of frequencies to be received are much greater than can be accommodated by conventional broad-banding techniques, yet the band of desired signals is not continuous in the ether spectrum. On the contrary, it is made up of what may be termed a lower band and an upper band spaced apart from each other by a wide range of unwanted signals in between. The lower band comprises channels 2 to 6, inclusive, with frequencies from 54 to 88 megacycles. The upper band consists of channels 7 to 13, inclusive, and includes frequencies from 174 to 216 megacycles. While a good TV antenna should give high gain performance throughout both of said bands, yet it is desirable to discriminate against the unwanted signals of FM radio and other sources which are transmitted in the intermediate frequency ranges between 88 and 174 megacycles.

With all of the above, it is also regarded as essential that the characteristic impedance of the antenna be such that it accomplish a reasonably good match with a 300 ohm twin lead transmission line throughout the entire band width covered. In addition, it is of extreme importance that the antenna possess well defined unidirectional characteristics on all channels to achieve the greatest possible freedom from interference and ghosts.

0f the antennas devised in the past, there has been some in which an eifort has been made to achieve broad band reception throughout the entire V. H. F. range, but the frequency range is too great to achieve high gain performance, and such antennas do not, of course, discriminate against the unwanted intermediate frequencies. Others have been designed to use one high frequency element intended to receive the signals of channels 7 to 13, with a lower frequency element and designed to respond to the signals of channels 2 to 6 inclusive. The present disclosure departs from both these practices, however, .by the provision of a new and dilferent type of radiator wherein a'single folded dipole is designed to respond to the signals in the lower frequency band, yet is provided with a relatively shorter central section arranged to respond to signals in the upper band. Thus it is unnecessary to provide more than one driven element in the antenna array. The signal element is resonant in either the lower band or upper band of wanted signals and thus provides a high degree of gain in all of the V. H. F. television channels, yet the antenna discriminates against the unwanted 88 to 174 megacycle signals.

The desired impedance characteristics are achieved by utilizing a single folded dipoleas the driven element in the antenna array. A highly efficient unidirectional radia- Patented Feb. 3, 195? tion pattern is achieved by the provision of two separate reflector assemblies. One of these reflectors is spaced substantially away from the driven dipole element, at a distance of a quarter wavelength at an intermediate frequency Within the lower band. A series of three shorter reflectors are more closely spaced with respect to the dipole, and are positioned behind the central zone and and zones thereof. These reflectors are spaced a distance of a quarter wavelength at an intermediate frequency within the upper band.

The invention is illustrated in the drawings of this specification in its commercial form, with a diagrammatic illustration of its component elements. In the drawings:

Figure 1 is a perspective view of a four bay fringe area antenna constructed in accordance with the present teachings;

Figure 2 is a diagrammatic plan view of the component elements of a single bay of the antenna.

As shown in Figures 1 and 2, the main driven element of the antenna array consists of a single folded dipole 10. This is preferably of tubular aluminum construction with one tube directly above the other at a spacing of two inches on centers. The upper span of the tube is mounted at its center and grounded on a cross arm 11. The inner ends of the lower span of the tube are adapted for connection to the leads of a conventional twin lead transmission line at theterrninals 12 and 13. The overall length L of the dipole 10 is substantially equal to a half wavelength at anintermediate operating frequency within the lower television band, but the precise dimensions of the various elements of the antenna have been modified from rule of thumb values to give broadband characteristics and uniform gain characteristics throughout the operating ranges, and the dimensions found to give most consistently good results are given hereinafter where the length L of the dipole 10 is 84 inches.

to center spacing of its two spans, the invention contemplates the use of relatively high Q conductor tubing for this driven element. The greatest diameter tubing that could be used with such spacing, while maintaining any separation of the two spans of the folded dipole, would be less than 2 inches. With the disclosed overall length of these spans of 84 inches, the L/D ratio of the conductor material is necessarily greater than 40 and, using conventional tubing of between 4 inch and 1 inch outside diameter, as is customary in the industry inch outside diameter being most common and naturally suggesting itself for use in the type of dipole disclosed), the L/D ratio would be greater than and normally around 200 or higher.

The term high Q conductor, as used in the appended claims, has reference to Q values at least as great as those resulting from the inherent minimum L/D ratio of about 40 which could be employed in adriven dipole having the above illustrative dimensions.

In the reception of signals within channels 2 to 6, inclusive, the entire dipole 10 functions substantially as a half wave dipole, being resonant as a half-wave dipole at an optimum frequency in the low band frequency range of those channels. The central section of the dipole 10 is provided, however, with a pair of coacting tubular aluminum line conductors 14 andlS spaced very close to the dipole and cut to a length substantially equal to one half wavelength at a mid-point in the high frequency band which, in the example illustratedin the drawings, is about three times the half-wave resonant frequency of the dipole 10. In practice, these conductors As will be obvious from the above illustrative figures for the length of the folded dipole and the center resonant as a half-wave dipole and are 28 in length, i. e., one third the length of the dipole It). The midpoints of the line conductors 14 and 15 are mounted on and grounded to the horizontal cross arm it, so that these tubes are centrally aligned with and coact with the central zone of the dipole 10 to form a resonant sec tion or zone, capable of high gain response with respect to television signals in channels 7 to 13 inclusive.

A lower band reflector 16, which may suitably be 110 inches long and which is also preferably of aluminum tube construction, is mounted on and grounded to the rear end of the cross arm 11, suitably 38 /2 inches behind the dipole It This positions the low frequency reflector at a point a little less than one quarter wavelength in said upper band behind the dipole 10.

A central or primary high frequency reflector fl, sunably 34 inches long, is also mounted on the cross arm 12, directly behind the folded dipole 10 and conductors 114- and 15. The spacing is such that the reflector 17 is spaced substantially a quarter wavelength away from the folded dipole lit) at its mean operating frequency, or suitably about 14 inches therefrom. Secondary high band reflectors 1S and 19 are mounted in insulating supports 20 at the opposite ends of the tube 17, and these reflectors are thus positioned substantially behind and similarly spaced from the outer end portions of the main dipole 10.

In practice it has been found that extreme high gain performance may be achieved by a double or four-bay antenna, with each bay consisting of the components shown in Figure 2. Such an antenna is shown in Figure 1, wherein the several bays A, B, C and. D are mounted in vertically spaced relationship on a common mast Z1 and are connected to a commontransmission line 22 by parallel wire stacking harnesses 23 and 24, joined by a four-bay connecting harness 25.

Having thus described my invention, what I claim as new and desire to secure by United States Letters Patsubstantially equal to a half wavelength at an intermediate frequency in said lower reception band; with a lower band reflector at least as long as said folded dipole mounted and grounded at its center and disposed parallel with and in the same horizontal plane as said folded dipole but spaced rearwardly therefrom a distance substantially equal to one quarter of said wavelength; a pair of relatively short line conductors of substantially equal length which is a half wavelength at an intermediate frequency in the upper reception band mounted and grounded at their centers and disposed parallel with and in spaced relationship in front and in back of a central zone of the aforementioned folded dipole, said line conductors being equally spaced from the dipole in such close proximity thereto that said line conductors and the central zone of the folded dipole comprise a transmission line section resonant to an intermediate frequency in the aforementioned upper reception band, such spacing being of the order of 4% of a half-wave length to which the dipole is resonant as a half-wave element; with a primary upper band reflector parallel with and in the same horizontal plane as said line conductors and spaced rearwardly therefrom a distance substantially equal to half their length, and a pair of secondary upper band reflectors disposed in parallel relation behind the outer end portions of said folded dipole.

2. A multiple channel television receiving antenna for operation throughout both an upper reception band consisting of a plurality of relatively high frequency channels and a lower reception band consisting of a plurality f relatively low frequency channels, said bands being .rated from each other by a wide range of unwanted rquencies; said antenna comprising, in combination, a sin gle driven element consisting of a horizontally disposed dipole constructed of a high Q conductor and having a substantially equal to a half wavelength at an interto frequency in said lower reception band; with a ower band reflector disposed parallel with said dipole but spaced rearwardly therefrom a distance substantially equal to one quarter of said wavelength; 2. pair of relatively short line conductors of substantially equal length which is a half wavelength at an intermediate frequency in the upper reception band disposed parallel with and in spaced relationship in front and in back of a central zone of the aforementioned dipole, said line conductors being equally spaced from the dipole in such close proximity thereto that said line conductors and the central zone of the dipole comprise a transmission line section resonant to an intermediate frequency in the aforementioned upper reception band, such spacing being of the order of 4% of a half-wave length to which the dipole is resonant as a half-wave element; with a primary upper band reflector parallel with said line conductors and spaced rearwardly therefrom a distance substantially equal to half their length, and a pair of secondary upper band reflectors disposed in parallel relation behind the outer end portions of said dipole.

3. A multiple channel television receiving antenna for operation throughout both an upper reception band consisting of a plurality of relatively high frequency channels and a lower reception band consisting of a plurality of relatively low frequency channels, said bands being separated from each other by a Wide range of unwanted frequencies; said antenna comprising, in combination, a single driven element consisting of a horizontally disposed folded dipole mounted and grounded at its center, said dipole being constructed of a high Q conductor and having a length substantially equal to a half Wavelength at an intermediate frequency in said lower reception band; with a' lower band reflector at least as long as said folded dipole mounted and grounded at its center and disposed parallel with and in the same horizontal plane as said folded dipole but spaced rearwardly therefrom a distance substantially equal to one quarter of said wavelength; a pair of relatively short line conductors of substantially equal length which is a half wavelength at an intermediate frequency in the upper reception band mounted and grounded at their centers and disposed parallel with and in spaced relationship in front and in back of a central zone of the aforementioned folded dipole, said line conductors being equally spaced from the dipole in such close proximity thereto that said line conductors and the central zone of the folded dipole comprise a transmission line section resonant to an intermediate frequency in the aforementioned upper reception band, such spacing being of the order of 4% of a half-wave length to which the dipole is resonant as a half-Wave element; with a primary upper band reflector parallel with and in the same horizontal plane as said line conductors and spaced rearwardly therefrom a distance substantially equal to half their length.

4-. A multiple channel television receiving antenna for operation throughout both an upper reception band consisting of a plurality of relatively high frequency channels and a lower reception band consisting of a plurality of relatively low frequency channels, said bands being separated from each other by a wide range of unwanted frequencies; said antenna comprising, in combination, a single driven element consisting of a horizontally disposed dipole constructed of a high Q conductor and having a length substantially equal to a half Wavelength at an intermediate frequency in said lower reception band; with a lower band reflector disposed parallel with said dipole but spaced rearwardly therefrom a distance substantially equal to one quarter of said wavelength; a pair of relatively short line conductors of substantially equal length which is a half wavelength at an intermediate frequency in the upper reception band disposed parallel with and in spaced relationship in front and in back of a central zone of the aforementioned dipole, said line conductors being equally spaced from the dipole in such close proximity thereto that said line conductors and the central zone of the dipole comprise a transmission line section resonant to an intermediate frequency in the aforementioned upper reception band, such spacing being of the order of 4% of a half-wave length to which the dipole is resonant as a half-wave element; with a primary upper band reflector parallel with said line conductors and spaced rearwardly therefrom a distance substantially equal to half their length.

5. A multiple channel television receiving antenna for operation throughout both an upper reception band consisting of a plurality of relatively high frequency channels and a lower reception band consisting of a plurality of relatively low frequency channels, said bands being separated from each other by a wide range of unwanted frequencies; said antenna comprising, in combination, a single driven element consisting of a horizontally disposed folded dipole constructed of a high Q conductor and having a length substantially equal to a half wavelength at an intermediate frequency in said lower reception band; a pair of relatively short line conductors of substantially equal length which is a half wavelength at an intermediate frequency in the upper reception band disposed parallel with and in spaced relationship in front and in back of a central zone of the aforementioned folded dipole, said line conductors being equally spaced from the dipole in such close proximity thereto that said line conductors and the central zone of the folded dipole comprise a transmission line section resonant to an intermediate frequency in the aforementioned upper reception band, such spacing being of the order of 4% of a half-wave length to which the dipole is resonant as a half-wave element; with a primary upper band reflector parallel with and in the same horizontal plane as said line conductors; said upper band reflector being of length at least equal to the length of said line conductors and spaced rearwardly therefrom a distance substantially equal to half their length; and a pair of secondary upper band reflectors disposed in parallel relation behind the outer end portions of said folded dipole.

6. A multiple channel television receiving antenna for operation throughout both an upper reception band consisting of a plurality of relatively high frequency channels and a lower reception band consisting of a plurality of relatively low frequency channels, said bands being separated from each other by a wide range of unwanted frequencies; said antenna comprising, in combination, a single driven element consisting of a horizontally disposed dipole constructed of a high Q conductor and having a length substantially equal to a half wavelength at an intermediate frequency in said lower reception band; a pair of relatively short line conductors of substantially equal length which is a half wavelength at an intermediate frequency in the upper reception band disposed parallel with and in spaced relationship in front and in back of a central zone of the aforementioned dipole, said line conductors being equally spaced from the dipole in .such close proximity thereto that said line conductors and the central zone of the dipole comprise a transmission line section resonant to an intermediate frequency in the aforementioned upper reception band, such spacing being of the order of 4% of a half-wave length to which the dipole is resonant as a half-wave element; with a primary upper band reflector parallel with said line conductors; said upper band reflector being of length at least d equal to the length of said line conductors and spaced rearwardly therefrom a distance substantially equal to half their length. 7

'7. An antenna for operation throughout both an upper frequency band and a lower frequency band, said antenna comprising, in combination, a single driven element consisting of a horizontally disposed folded dipole mounted and grounded at its center, said dipole being constructed of a high Q conductor and having a length substantially equal to a half wavelength at an intermediate frequency in said lower frequency band; a pair of relatively short line conductors of substantially equal length which is a half wavelength at an intermediate frequency in the upper frequency band mounted and grounded at their centers and disposed parallel with and in spaced relationship in front and in back of a central zone of the aforementioned folded dipole, said line conductors being equally spaced from the dipole in such close proximity thereto that said line conductors and the central zone of the folded dipole comprise a transmission line section resonant to an intermediate frequency in the aforementioned upper frequency band, such spacing being of the order of 4% of a half-Wave length to which the dipole is resonant as a half-wave element; with a primary upper band reflector parallel with and in the same horizontal plane as said line conductors; and spaced therefrom, and at least one secondary upper band reflector.

8. An antenna for operation throughout both an upper frequency band and a lower frequency band, said antenna comprising, in combination, a single driven element consisting of a horizontally disposed folded dipole mounted and grounded at its center, said dipole being constructed of a high Q conductor and having a length substantially equal to a half wave length at an intermediate frequency in said lower frequency band; a pair of relatively short line conductors of substantially equal length which is a half wavelength at an intermediate frequency in the upper frequency band mounted and grounded at their centers and disposed parallel with and in spaced relationship in front and in back of a central zone of the aforementioned "folded dipole, said line conductors being equally spaced from the dipole in such close proximity thereto that said line conductors and the central zone of the folded dipole comprise a transmission-line section resonant to an intermediate frequency in the aforemen tioned upper frequency band, such spacing being of the order of 4% of a half-wave length to'which the dipole is resonant as a half-wave element; with a primary upper band reflector parallel with and in the same horizontal plane as said line conductors and spaced therefrom.

9. An antenna for operation throughout both an upper frequency band and a lower frequency band, said antenna comprising, in'combination, a single driven element consisting of a horizontally disposed folded dipole mounted and grounded at its center, said dipole being constructed of a high Q conductor and having a length substantially equal to a half wavelength at an intermediate frequency in said lower frequency band; and a pair of relatively short line conductors of substantially equal length which is a half wavelength at an intermediate frequency in the upper frequency band mounted and grounded at their centers and disposed parallel with and in spaced relationship in front and in back of a central zone of the aforementioned folded dipole, said line conductors being equally spaced from the dipole'in such close proximity thereto that said line conductors and the central zone of the folded dipole comprise a transmission line section resonant to an intermediate frequency in the aforementioned upper frequency band, such spacing being of the order of 4% of a half-wave length to which the dipole is resonant as a half-wave element.

10. An antenna for operation throughout both an' upper frequency band and a lower frequency band, said ment consisting of a dipole constructed of a high Q conductor and having a length substantially equal to a half wavelength at an intermediate frequency in said lower frequency band; a pair of relatively short line conductors of substantially equal length which is a half wave length at an intermediate frequency in the upper frequency hand disposed in spaced relationship in front and in bac; of a central zone of the aforementioned dipole in such close proximity thereto that said line conductors and the dipole comprise a transmission line section rcsonant to an intermediate frequency in the aforementioned upper frequency band, such spacing being of the order of 4% of a half-wave length to which the dipole is resonant as a half-wave element; with a primary upper band reflector parallel with said line conductors and spaced therefrom, and at least one secondary upper hand reflector.

11. An a tenna for operation throughout both an upper frequency band and a lower frequency band, said antenna comprising, in combination, a single driven element consisting of a dipole constructed of a high Q conductor and having a length substantially equal to a half wavelength at an intermediate frequency in said lower frequency band; and a pair of relatively short line conductors of substantially equal length which is a half wavelength at an intermediate frequency in the upper frequency band disposed in spaced relationship in front and in back of a central zone of the aforementioned dipole in such close proximity thereto that said line conductors and the dipole comprise a transmission line section rcsonant to an intermediate frequency in the aforementioned upper frequency band, such spacing being of the order of 4% of a half-Wave length to which the dipole is resonant as a half-wave element.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,960 Lorusso Mar. 8, 1955 Re. 24,413 Weiss Jan. 7, 1958 2,268,460 Brown Jan. 6, 1942 2,580,798 Kolster Jan. I, 1952 2,688,083 Hills Aug. 31, 1954 2,705,283 Thomas Mar. 29, 1955 2,726,390 Weiss Dec. 6, 1955 

